This invention relates to a displacement control device for use in variable displacement pumps. The objects of the displacement control of variable displacement pumps can be broadly classified into the following three items.
(1) Displacement controls in accordance with the instruction of the operator.
(2) Controls of the input torque of the pump.
(3) Prevention of generation of excessive or overshoot pressures.
The prior art devices have been disadvantageous in that they can meet the above-mentioned requirements individually, however, cannot satisfy all such requirements.
In case of the control device comprising linkages and cams, controls cannot be made to limit the total input torque of a plurality of variable displacement pumps, and the prior art control devices for limiting the total input torque of a plurality of variable displacement pumps requires the condition that the displacements of respective pumps are equal, and therefore they cannot meet the requirements in the above-mentioned items (1) and (3).